The present invention relates to a hierarchical bus type multidirectional multiplex communication system.
The hierarchical bus type multidirectional multiplex communication system has been composed of, for example, a master station and a plurality of relay stations and tributary stations hierarchically connected to the master station respectively. The hierarchical bus type multidirectional multiplex communication system is structured such that, when a fault is generated in any one of the master station or the relay stations of the system, a relay station positioned one rank lower than the master station or the relay station having the fault can perform the same function as the master station does, thereby making a plurality of lower order tributary stations positioned lower than the relay station able to communicate normally.
However, to realize the above, the relay station positioned one rank lower than the fault-generated master station or relay station must have a complex function the same as the master station, because it must control the lower order stations in the same way as the master station by performing switching control based on the preliminarily prepared station data of the lower order stations.